An investigation of models of the IP3R channel in Xenopus Oocyte

Abstract

We consider different models of inositol 1,4,5-trisphosphate (IP3) receptor (IP3R) channels in order to fit nuclear membrane patch clamp data of the stationary open probability, mean open time, and mean close time of channels in the Xenopus oocyte. Our results indicate that rather than to treat the tetrameric IP3R as four independent and identical subunits, one should assume sequential binding-unbinding processes of Ca2+ ions and IP3 messengers. Our simulations also favor the assumption that a channel opens through a conformational transition from a close state to an active state.